Nanostructuring polycristalline gold films by Ar ion beam sputtering

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Nanostructuring polycristalline gold films by Ar
ion beam sputtering
Institute of metals and technology, Lepi pot 11,
1000 Ljubljana, Slovenija Dipartimento di Fisica,
Via Dodecaneso 33, 16146 Genova, Italy

• B. etina Batic, A. Toma, M. Jenko, F. Buatier de
  Mongeot

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Nanostructuring surfaces by ion beam sputtering
Besides removing material, surface erosion
process gives rise to pronounced topographical
evolution.
Erosive instability
Surface diffusion
Off-normal ion bombardment with energetic
particles leads to development of periodically
modulated structures.
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Single Crystal Metals the Ag(001) case
Ne ions, q 70, T 180 K, Ei 1 KeV, ? 5
mA/cm2 (2.6?10-2 MLNe/s)
300 sec
600 sec
1200 sec
180 nm
Surface roughness and ripple wavelength follow a
time power law. The same on Cu(110) PRL 81
(1998) 2735 Co/Cu(001) PRL 91 (2003) 167207
Fe/Ag(001) PRB 75 (2007) 054407
What about supported polycrystalline films?
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Samples

• We prepared 2 different sets of samples of 150 nm
  Au on glass
• Thermally evaporated (Physical Vapour deposition
  PVD) (1)
• Sputter deposited (2)

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2
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We also used commercially obtained Au film (150
nm) on mica (3)
Glass
Au target
Au crucible
Ar ions
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Grain size distribution
Grain size characterisationSEM and AFM images
PVD samples
0,06
0,04
0,02
0,00
surface coverage
0
20
40
60
80
100
120
140
0,06
Sputter deposited samples
0,04
0,02
0,00
0
20
40
60
80
100
120
140
mean diameter nm
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Sample sputtering
Ion Beam Sputtering (IBS) _at_
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Morphology evolutionAu sputter deposited samples
0 min
15 min
20 min
35 min
65 min
75 min
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Au sample bombarded 20 min
The wavelength is in the range 80 100 nm
The average grain size is 90nm
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Morphology evolution PVD samples
35 minutes
75 minutes
Initial state
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Morphology evolution mica (AFM images)
15 min
15 min
flat
7 min
flat
7 min
65 min
20 min, (713)
35 min
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Morphology evolution - mica (SEM images)
Initial state
15 min
30 min
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Roughness and wavelength evolution
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1.
Glass
We investigated three thin Au films, prepared by
different methods, showing the difference in
initial grain sizes.
Au target
Ar ions
2.
Surface reorganization during sputtering process
by Ar ions was investigated, revealing the
formation and evolution of a wavelike structure.
The grain size plays an important role in the
wavelength selection process as can be seen by
comparing the films with large and the films with
small grains.